Spatial and Temporal Distribution of Total Mercury (T-Hg) in Different Water Bodies of Nam Co, Tibetan Plateau
青藏高原纳木错流域水体总汞的时空分布特征

To investigate the tempo-spatial distribution of total mercury (T-Hg) concentration in water bodies in the Nam Co basin on the Tibetan Plateau, inflowing river water and surface lake water samples were collected from 2007 to 2010. The T-Hg concentration and its relationship with precipitation and river runoff were analyzed. The results showed that the average T-Hg concentration was (1.09±0.73) ng·L-1 and (2.87±2.59) ng·L-1 for surface lake water and river water, respectively, both of which were significantly lower than those of Hg contaminated waters. T-Hg concentration in off-shore lake water was much higher during the monsoon season than in the non-monsoon season, and its level and spatial variation were significantly greater than those in central lake water. T-Hg concentration in river water showed significant seasonal variations with the highest values during the monsoon season and the lowest during the post-monsoon season, which were in accordance with the variations of precipitation. A fixed point observation at Niyaqu River indicated that the temporal changes of the T-Hg concentrations in river water were in accordance with those of the runoff. The spatial distribution features of T-Hg concentrations in inflowing river water varied in different periods, possibly resulting from the differences in drainage areas, background mercury levels in soils, and water supplies for rivers at different locations of the Nam Co basin.